In three-dimensional measurement, the location of surface points of an object may be obtained for a plurality of applications including the measurement of the intraoral cavity. Methods for direct optical measurement of teeth and manufacture of products such as crowns and dentures, are known. Herein, digital data may be obtained and used for the computer-assisted design (CAD) or computer assisted manufacture (CAM) of tooth replacements without having to make any physical impressions of the teeth. Such methods include, for example, confocal measurement techniques such as is described in U.S. Pat. No. 6,697,164B1. Herein, a digital three-dimensional surface model that is inherently monochromatic may be provided without any color information.
In some systems, a 3D camera system for 3D and color measurement may use the same optics for color measurement as the optics for 3D measurement. In such systems, the optical paths for 3D measurement and color measurement may be configured to distribute the light onto different sensors. However light scattering and reflections due to the simultaneous usage of at least some optics for different purposes (illumination, detection, etc.) may occur, effectively reducing image quality of the color images.
U.S. patent application Ser. No. 16/003,592 and U.S. patent application Ser. No. 16/003,628 disclose devices, methods and systems for generating dynamic projection patterns in a camera for 3D measurement. They are hereby incorporated by reference in their entirety for background disclosure purposes.
U.S. Pat. No. 3,681,519A discloses a handheld dental camera for carrying out optical 3D measurement comprising a light source, achromatic objective and a color sensor wherein the light source may be configured to emit a beam that may be focused onto the surface of an object by means of the chromatic objective. The beam may then be reflected by the surface and the reflected beam may be capable of being detected by the color sensor for measurement.
U.S. Pat. No. 7,787,132B2 describes a chromatic confocal method and apparatus for the rapid three-dimensional measurement of an object using an array of polychromatic point light sources, a planar detector matrix, a beam splitter for lateral spectral separation, and an objective for illuminating and recording the object. Spectral defined reference light bundles may be generated, injected into a detection beam path through a reference beam path and, following spectral splitting, focused on the detector matrix as reference image points, wherein laterally shifted sub-matrices may be numerically defined on the detector matrix for spectral analysis of the object light, which sub-matrices may be implemented as spectral cells for three-dimensional measurement of the shape of the object
U.S. patent application Ser. No. 14/268,201 illustrates a method of performing a three-dimensional scan of an object including applying an optical contrast powder to the object and illuminating the object with light. A first and a second two-dimensional (2D) color image data corresponding to the object are generated and a first and a second 2D monochrome image data corresponding to the object may be generated using the first and second 2D color image data. 3D data corresponding to the object may then be generated using the first and second monochrome 2D image data and color 3D image data corresponding to the object may be generated by adding color information to the 3D data.
U.S. patent application Ser. No. 10/007,715 shows a method and an apparatus for acquiring surface topography wherein the surface being acquired may be illuminated by illumination sources with patterns of light from an optical perspective and the light reflected off the surface may be captured by image sensors from an optical perspective that may be different from the perspective of the illumination. The images obtained may be of the surface with one or more patterns superimposed upon the surface. The surface topography may be computed with a processor based upon the patterned image data, a known separation between the illumination sources and the imaging sensors, and knowledge about how the patterns of light are projected from the illumination sources.